The present invention relates to techniques for varying characteristics of sounds.
So far, a variety of techniques have been proposed for imparting musical effects to sounds uttered or generated by users (hereinafter referred to as “input sounds”). For example, Japanese Patent Application Laid-open Publication No. HEI-10-78776 (in particular, see paragraph 0013 and FIG. 1 of the publication) discloses a technique in accordance with which a concord sound (i.e., sound forming a chord with an input sound), generated by converting the pitch of the input sound, is added with the input sound and outputs the result of the addition. Even where there is only one sound-uttering or sound-generating person, the arrangements disclosed in the No. HEI-10-78776 publication (hereinafter referred to as “patent literature”) can generate sounds as if a plurality of persons were singing different melodies in ensemble. For example, if the input sound is a performance sound of a musical instrument, the disclosed arrangements can generate sounds as if different melodies were being performed in ensemble via a plurality of musical instruments.
There are known various forms of ensemble singing and ensemble musical instrument performance, among which are the so-called “chorus” where a plurality of singers or performers sing or perform different melodies and the so-called “unison” where a plurality of singers or performers each sing or perform a same or common melody. The arrangements disclosed in the above-identified patent literature, where a consonant sound is generated by converting the pitch of an input sound, can not impart an input sound with an effect of a “unison” where a plurality of singers or performers each sing or perform a same or common melody, although the disclosed arrangements can generate sounds with an effect of a “chorus” where a plurality of singers or performers sing or perform different melodies. Even with the arrangements disclosed in the above-identified patent literature, it would be possible to impart a unison effect, in a fashion, as though a plurality of singers or performers were each singing or performing a common melody, by outputting, along with the input sound, a sound created by converting only an acoustic characteristic (sound quality) of the input sound without changing the pitch of the input sound. In this case, however, it is essential to provide arrangements for converting the input sound characteristic per input sound constituting unison sounds. Thus, in cases where unison sounds by a plurality of persons are to be achieved, electric circuitry employed for converting the characteristic of each input sound by hardware, such as a DSP (Digital Signal Processor), would become great in size or scale. If the input sound characteristic conversion is performed by software, on the other hand, processing load on an arithmetic operation device would become excessive.